[AT] Valve Seat Inserts

[Steve W.]

Dean VP wrote:
> Found a term in this company’s price list that rings some memories
> but really hazy ones.    Could someone explain when and why “Valve
> Seat Inserts”  are used rather than replacing the whole valve guide?
> Yes, they are a little less expensive but not that much  Please
> refresh my hazy memory from the 50’s.
> 
> 
> 
> Dean VP
> 

Different parts. The valve guide holds the valve stem and keeps it in 
position. The valve seat is the ground part of the port in the head that 
the valve face seals against. The reason for the inserts are a few, one 
is that you might have a head with damaged or eroded seats and the 
valves won't seal. You machine out the worn/damaged area, press in the 
inserts and either peen the edge or more commonly you bore the area for 
the seat with a step so the seat locks into the head, to install you 
freeze the insert and heat up the head. Then the two parts lock together 
as the temperatures normalize. Have done both and prefer the second option.

-- 
Steve W.